Slate.com's WIlliam Saletan has a brief article discussing ADHD and its evolutionary origins. He writes that an understand of its potential usefulness in the past may help our society to adopt to ADHD rather than forcing individuals with ADHD to adopt to our societal standards. He says,

. . . . A new study suggests that
this ADHD-friendly world may actually be part of our past. The study, led by Dan Eisenberg of Northwestern University and published in BMC Evolutionary Biology,
examined a Kenyan tribe called the Ariaal. Part of the tribe has
recently settled into an agricultural community. Another part remains
nomadic. The tribesmen were tested for DRD4 7R, a genetic variant that,
Eisenberg notes, "has been linked to greater food and drug cravings, novelty-seeking, and ADHD symptoms." He and his colleagues report:

I don't know whether
the speculated reasons for the gene's benefits will pan out. But the
benefits do seem real. And that finding suggests two things. First, we
should be careful about designating diseases and disease genes. Traits
that are harmful in one setting can be helpful in another. Advantages
or "defects" that we think of as natural may actually be products of
our cultural decisions. As Eisenberg puts it, we might "begin to view ADHD as not just a disease but something with adaptive components."

Second,
our society may be the wrong place to assess a gene's evolutionary harm
or benefit. As the authors note, "[N]on-industrialized or subsistence
environments … may be more similar to the environments where much of
human genetic evolution took place." . . . .

The lesson of the Ariaal study is simply that society can adapt to
genes instead of the other way around. Maybe we don't have to screen and chuck embryos
for every "disease" gene, or drug the kids once they're born. Maybe we
can put ADHD kids in educational settings more like the dynamic
environment of our nomad forebears. And maybe we can raise kids with
fat-storage genes in settings less full of food. . . .